System and method of message-based power management

ABSTRACT

Briefly, system and method for message-based power management which may be used, for example, in computer systems and communications networks. Embodiments of the present invention may include, for example, a device connected to a power management controller (PMC); the device and/or the PMC may send, receive, and/or process power management event (PME) messages. Embodiments of the present invention may operate using links in communicative and/or non-communicative modes. Embodiments of the present invention may include a switch, to send/receive, process, create, re-format and/or route one or more PME message on behalf of various devices, for example, a Peripheral Component Interconnect (PCI) device.

BACKGROUND OF THE INVENTION

[0001] In computers and other electronic systems and devices, there maybe a need to inform a Power Management Controller (PMC) about a PowerManagement Event (PME) that may require attention. A PME may occur, forexample, when a user presses a key on a keyboard or moves a mouse, inorder to “wake up” a computer or a monitor from “sleep mode” orpower-saving mode. Another example of a PME is receiving an incomingtransmission by a modem or a facsimile operating, e.g., in “idle” or“stand-by” mode.

[0002] Applications and devices based on PME-related transmissions maybe used, for example, in networks, servers, desktop and mobilecomputers, wireless communications devices, cellular devices, andhigh-speed interconnects; for example, an Ethernet controller mayrestore operation of a system from a “sleep mode” upon receipt of apredefined network transmission.

[0003] PME signals initiated by multiple Peripheral ComponentInterconnect (PCI) devices may be merged and routed as a single input toa PMC, for example, by tying together communication wires, e.g., in a“wired-OR” configuration. Power management software may perform anetwork scan to locate the originating device or devices. However,actual implementations, for example, some operating systems, may fail inperforming the scan across multiple devices and/or across multiple databuses. As a result, the PME-related transmissions of each PCI bus arerouted separately, resulting in decreased system efficiency, increasedpin count and compatibility problems.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The subject matter regarded as the invention is particularlypointed out and distinctly claimed in the concluding portion of thespecification. The invention, however, both as to organization andmethod of operation, together with features and advantages thereof, maybest be understood by reference to the following detailed descriptionwhen read with the accompanied drawings in which:

[0005]FIG. 1 is a schematic illustration of a communications networkincorporating a message-based power management system in accordance withexemplary embodiments of the present invention;

[0006]FIG. 2 is a schematic flowchart depicting a message-based powermanagement method in accordance with exemplary embodiments of thepresent invention, applied to a communicative link of a communicationsnetwork;

[0007]FIG. 3 is a schematic flowchart depicting a message-based powermanagement method, in accordance with exemplary embodiments of thepresent invention, applied to a non-communicative link of acommunications network;

[0008]FIG. 4 is a schematic flowchart depicting a handshake operationwhich may be used by a communications network according to exemplaryembodiments of the present invention;

[0009]FIG. 5 is a schematic illustration of a communications networkincorporating a switch and a message-based power management system inaccordance with exemplary embodiments of the present invention;

[0010]FIG. 6 is a schematic illustration of a switch in accordance withan exemplary embodiment of the present invention, which may be used inconjunction with the communications network of FIG. 5; and

[0011]FIG. 7 is a schematic conceptual diagram of various modes ofoperation of a communications link used in conjunction with acommunications network in accordance with exemplary embodiments of thepresent invention.

[0012] It will be appreciated that for simplicity and clarity ofillustration, elements shown in the figures have not necessarily beendrawn to scale. For example, the dimensions of some of the elements maybe exaggerated relative to other elements for clarity. Further, whereconsidered appropriate, reference numerals may be repeated among thefigures to indicate corresponding or analogous elements.

DETAILED DESCRIPTION OF THE INVENTION

[0013] Embodiments of the present invention may solve the above problemsby providing a mechanism to indicate the source of a Power ManagementEvent (PME) and/or to provide other data regarding a PME. Embodiments ofthe present invention may achieve these solutions using, e.g., in-bandmessaging, whereby control messages are communicated via the samechannel with the main traffic served by a device, and/or out-of-bandmessaging, whereby control messages are communicated via a separate,e.g., dedicated, channel. Additionally or alternatively, embodiments ofthe present invention may bring a network or a link into and out of anon-communicative state. Furthermore, embodiments of the presentinvention may send, receive and/or process PME messages on behalf ofcertain devices, for example, Peripheral Component Interconnect (PCI)devices connected to a network.

[0014]FIG. 1 is a schematic illustration of a communications network 100incorporating a message-based power management system in accordance withexemplary embodiments of the present invention. Network 100 may includeat least one power-controlled device 110 and at least one PowerManagement Controller (PMC) 120, connected via a communication link 130.

[0015] It will be appreciated that the term “network” as used herein mayinclude any system or sub-system which includes any combination ofhardware and/or software components and/or devices and/or systems, forexample, a computer, a server, a peripheral device, and the like.Additionally or alternatively, the term “network” may include a wired orwireless Local Area Network (LAN), an Ethernet network, a token ringnetwork, or any other suitable type of communications network.

[0016] Network 100 may be implemented, for example, as a system or asub-system, e.g., a computer, which may include device 110, PMC 120, andlink 130, as well as other components, for example, a processor (notshown). Alternatively, in an exemplary embodiment of the presentinvention, network 100 may be implemented using any suitable type ofcommunications network including device 110, PMC 120, and link 130.

[0017] Device 110 may include, for example, a desktop computer, a laptopor notebook computer, a server, a printer, a scanner, a monitor, acopier, a backup tape, or any other suitable device that may beassociated with network 100. It is noted that device 110 may include,for example, a stand-alone unit or a sub-unit of another device orsystem. Additionally or alternatively, device 110 may include one ormore software component.

[0018] It will be appreciated that the terms “controller”, “powermanagement controller” and/or “PMC” as used herein may include anysuitable system, sub-system, unit, device, controller card, processor,and/or any combination of hardware and/or software components.

[0019] PMC 120 may include any suitable PMC that may be associated withnetwork 100. It is noted that in embodiments of the present invention,PMC 120 may include, for example, a stand-alone unit or a sub-unit ofanother device or system. In an exemplary embodiment of the presentinvention, PMC 120 may be implemented, for example, using a computerserver, a processor, a controller card, or one or more sub-unit of acomputer system. Additionally or alternatively, PMC 120 may include oneor more software component.

[0020] Link 130 may include any suitable type of link associated withnetwork 100. Link 130 may include, for example, a wired or wirelessconnection, and may be active, non-active, communicative ornon-communicative, as described in detail herein. Additionally, link 130may be implemented using any suitable combination of hardware and/orsoftware to establish network communication between components ofnetwork 100.

[0021] In accordance with embodiments of the invention, a PowerManagement Event (PME) may include, for example, any event that requiressystem action, for example, action related to power management. In anexemplary embodiment of the present invention, a PME message mayinclude, for example, a data packet sent and/or received in order toresume operation of a device, for example, device 110, from a low-power“sleep mode”.

[0022] Upon occurrence of a PME, device 110 may send a data-bearing PMEmessage to PMC 120. Although the present invention is not limited inthis regard, the PME message may include data indicating the source ofthe originating device, for example, the source address of device 110.In an embodiment of the present invention, such data may include, forexample, the Internet Protocol (IP) address of device 110. Additionallyor alternatively, the PME message may include data by which theoriginating device may be identified, accessed and/or located, forexample, data representing an indication of “Plug-and-Play modem model123” or “Laser printer connected to bus number 2”. Additionally oralternatively, the PME message may include other data indicating theoriginating device and/or its operation and/or its properties, forexample, data representing an indication of “Operating at 56 kilobitsper second”, or “Operating with Interrupt Request (IRQ) 5”.

[0023] Additionally or alternatively, in embodiments of the presentinvention, the data-bearing PME message may include, for example, dataindicating a property of the PME that initiated the PME message, and/ordata indicating the type of PME that initiated the PME message. Thisdata may be based on a pre-defined list or lookup table of propertiesand/or types of PME, for example, a PME that requires a device to bebrought into “sleep mode”, a PME that requires a device to be broughtinto “active mode”, a PME that requires further processing operations bya processor, a PME of type “Incoming facsimile communication”, a PME oftype “User pressed a key”, and the like. Such types may be pre-definedin accordance with specific design requirements, and may includesub-types to allow more detailed classification of the PME.

[0024] Additionally or alternatively, in embodiments of the presentinvention, the data-bearing PME message may include any other suitabledata which may be relevant to the PME and/or to operations that need tobe performed in conjunction with the PME, in accordance with specificimplementations and/or design requirements.

[0025] In embodiments of the present invention, PMC 120 may receive thePME message and probe the originating device, e.g., device 110, inaccordance with the content of the PME message. Additionally oralternatively, other predefined tasks may be performed; for example, ifPMC 120 brings a processor out of “sleep mode”, then the processor,which may include hardware and/or software, may probe for the sourceaddress of device 110. It is noted that in embodiments of the presentinvention, device 110 may initiate a PME message on various PMEs, forexample, on the arrival of a pre-determined data packet or apre-determined type of data packet, or on a change in the communicationmode of link 130. Device 110 may contain additional information aboutthe PME, and may store information, for example, on a data packet thatarrived from network 100 and initiated the PME. In embodiments of thepresent invention, information about the PME may be included in the PMEmessage, and/or may be stored in a memory associated with device 110 forprobing.

[0026] Embodiments of the present invention are described herein in thecontext of two operational modes of link 130, namely, a CommunicativeMode (C-mode) and a Non-Communicative Mode (NC-mode). A C-mode may bedefined as a mode in which link 130 is either in an active state, e.g.,able to transfer data, or capable of being brought into active state. Itwill be appreciated that in embodiments of the present invention, link130 maybe switched and/or converted from C-mode to NC-mode, or viceversa, e.g., link 130 may be brought from C-mode to NC-mode, or viceversa.

[0027] A NC-mode may be defined as a mode in which the communicationchannel of link 130 is disabled, e.g., when link 130 is not suppliedwith power and/or a clock signal that may be essential for communicativeoperation of link 130. Methods in accordance with embodiments of thepresent invention may include sending and/or receiving PME messages overlink 130, in both the C-mode and the NC-mode, as described in detailbelow.

[0028] Reference is now made also to FIG. 2, which is a schematicflowchart depicting a message-based power management method inaccordance with exemplary embodiments of the present invention, appliedto network 100 when link 130 is in C-mode. The method may begin, asindicated at block 210, when a PME occurs, for example, at device 110. APME message may be sent from device 110, as indicated at block 220, andreceived by PMC 120, as indicated at block 230. PMC 120 may probe theoriginating device, e.g., device 110, as indicated at block 240. Asdescribed above, such probing may be performed to obtain additionalinformation about the PME, which may be stored in device 110.

[0029] Optionally, in embodiments of the present invention, as indicatedat block 250, additional tasks may be performed in accordance with thecontent of the PME message. For example, PMC 120 may “wake up” aprocessor, which may probe device 110 and obtain data about the PME thatthe processor needs in order to handle the PME. In an exemplaryembodiment of the present invention, if the PME message is an incomingfacsimile transmission, then a fax and/or a fax/modem and/or a processorreceiving the transmission may be brought out of “sleep mode” and/or mayprocess the transmission. It is noted that using link 130 in C-mode, aPME message may be transferred from device 110 to PMC 120 using themethod of FIG. 2 or any other suitable method in accordance withembodiments of the present invention.

[0030] Reference is now made to FIG. 3, which is a schematic flowchartdepicting a message-based power management method in accordance withexemplary embodiments of the present invention, applied to network 100when link 130 is in NC-mode. The method may begin, as indicated at block310, when a PME occurs, for example, at device 110. As indicated atblock 312, device 110 may notify or signal PMC 120 on the need to switchlink 130 from NC-mode to C-mode. Such notification or signaling may beout-of-band, i.e., using a predefined signal transferred via a dedicatedwire that connects device 110 with PMC 120. Additionally oralternatively, such notification or signaling may be in-band, i.e.,through link 130, for example, by transmitting energy through the linkin accordance with PCI Express Specification as described in section4.3.2.4 (Beacon), Revision 1.0, Jul. 22, 2002, and/or using any othersuitable transmission protocol.

[0031] As indicated at block 315, link 130 may be switched from NC-modeto C-mode. An intervention of PMC 120 may be required in order to switchlink 130 from NC-mode to C-mode. Such intervention may include, forexample, PMC 120 restoring clock and/or power to link 130.

[0032] A PME message may be sent from device 110, as indicated at block320, and received by PMC 120, as indicated at block 330. PMC 120 mayprobe the originating device, e.g., device 110, as indicated at block340, to obtain additional information about the PME stored in device110. Optionally, as indicated at block 250, additional tasks and/oroperations may be performed in accordance with the content of the PMEmessage, for example, the PME message may contain instructions and/ordata to allow processing of an incoming transmission. Such additionaltasks and/or operations may be performed, for example, by PMC 120, bydevice 110, by another device or a processor associated with network100, and/or by any other suitable hardware and/or software component orcomponents. It is noted that using link 130 in NC-mode, a PME messagemay be transferred from device 110 to PMC 120, for example, after link130 is switched from NC-mode to C-mode.

[0033] In embodiments of the present invention, it may be desired toswitch link 130 from C-mode into NC-mode, for example, in order toconserve power during long idle periods. Switching link 130 into NC-modemay include, for example, a “handshake” operation between device 110 andPMC 120, which operation may be performed in accordance with apredefined protocol. Although the present invention is not limited inthis regard, the handshake operation may allow device 110 and/or PMC 120to prepare for NC-mode, for example, to allow device 110 to “arm” itssignal-generating circuits or gate internal clocks in preparation forclock removal. Additionally or alternatively, in embodiments of thepresent invention, the handshake operation may indicate to device 110and/or PMC 120 that power and/or clock is about to be suspended and/orremoved, and/or that sending a PME message may become unreliable, from acertain point in time onward.

[0034] Reference is now made to FIG. 4, which is a schematic flowchartdepicting a handshake operation which may be used by network 100according to exemplary embodiments of the present invention. PMC 120 maysend a “turn-off” message to device 110 and/or to all devices connectedto PMC 120, as indicated at block 410. Device 110 may receive the“turn-off” message, as indicated at block 420, and may perform suitablepreparation tasks before clock and/or power removal, as indicated atblock 430. Device 110 may send to PMC 120 an acknowledgment message, asindicated at block 430. It is noted that, in embodiments of the presentinvention, several acknowledgment messages may be accumulated and/ormerged by one or more intermediate unit, and may be routed and/or sentby such one or more intermediate unit to PMC 120, either in theiroriginal format or in a modified format. PMC 120 may receiveacknowledgment messages from several or all devices connected to PMC120, as indicated at block 450. Additionally or alternatively, PMC 120may switch link 130 and/or other links of network 100 into NC-mode, asindicated at block 460.

[0035] In embodiments of the present invention, an acknowledgmentmessage sent by device 110 to PMC 120 may also trigger a “flush”operation for earlier PME messages, thereby to push ahead any pendingPME messages. It is noted that, in embodiments of the present invention,for example, embodiments that may operate in accordance with PCIordering rules, an acknowledgment message may be held in queue behindearlier PME messages and, therefore, earlier PME messages may reach PMC120 prior to power and/or clock removal. In embodiments of the presentinvention, an acknowledgment message that is generated while one or morePME message are being communicated through network 100 may be held inqueue behind earlier PME messages and may not bypass such earlier PMEmessages.

[0036] It is noted that in embodiments of the present invention, link130 may be switched from NC-mode to C-mode, or vice versa, for example,using in-band messaging and/or out-of-band messaging. The messagingprotocol may follow, for example, the PCI Express specificationpublished by PCI Special Interest Group (PCI-SIG) in July 2002, or usingany other suitable protocol for changing the mode of operation of link130.

[0037] In embodiments of the present invention, several PME messages maybe received by PMC 120 from several devices substantiallysimultaneously. In such a case, PMC 120 may not be able to store and/orprocess several concurrent PME messages, and thus PMC 120 may be forcedto “drop” or ignore some of the PME messages. To avoid this problem, inembodiments of the present invention, communicating devices, forexample, device 110, may periodically re-send a certain PME message toPMC 120, until receiving an acknowledgment message from PMC 120 that thePME message has been received and/or processed.

[0038] Reference is now made to FIG. 7, which schematically illustratesa conceptual diagram of various modes of operation of a communicationslink, for example, link 130 of FIG. 1, used in conjunction with acommunications network in accordance with exemplary embodiments of theinvention. It will be appreciated that the conceptual diagram of FIG. 7is shown for demonstrative purposes only, and that other modes and/orsequences of operation of communication links are also within the scopeof embodiments of the invention.

[0039] Reference is now made to FIG. 5, which is a schematicillustration of a communications network 550 incorporating at least onePME message-generating switch 530 and a message-based power managementsystem in accordance with exemplary embodiments of the presentinvention. Network 550 may include, for example, at least one PCI device510 and at least one PMC 520. PC device 510 maybe connected to switch530 by bus 515, and switch 530 maybe connected to PMC 520 by link 525.

[0040] PCI device 510 may include, for example, any device which may beconnected and/or may operate in accordance with one or more PCIspecification. PCI device 510 may initiate a PME by sending a PME signalto PMC 520, however, PCI device 510 may not be able to inform PMC 520about the origin of the PME. In accordance with embodiments of thepresent invention, switch 530 may be used to connect PCI device 510 tonetwork 550 and/or to PMC 520, and to send, receive and/or process PMEmessages on behalf of PCI device 510 and/or on behalf other devicesconnected to switch 530.

[0041] In an embodiment of the present invention, a PME signal mayoriginate from PCI device 510, and may be received by switch 530, forexample, using bus 515. Switch 530 may send a PME message to PMC 520 onbehalf of PCI device 510. The data contained in the PME message mayidentify or locate, for example, PCI device 510 and/or bus 515 to whichPCI device 510 is connected. Additionally or alternatively, powermanagement software may be used to probe bus 515 which was identified bythe PME message sent by switch 530, to identify a property (e.g., anidentification code) of the device, for example, PCI device 510, thatoriginated the PME signal.

[0042] It will be appreciated by persons skilled in the art that switch530 may be used to create, construct, format, process, handle, sendand/or receive a PME message on behalf of one or more device, or abranch of several devices, which may not be able by themselves toperform such tasks, entirely or in accordance with desired requirementsor formats. Additionally or alternatively, in embodiments of the presentinvention, switch 530 may be used to route, re-create, re-constructand/or re-format a PME message, such as, for example, to convert a PMEmessage into a certain format, protocol or specification. Additionallyor alternatively, switch 530 may be used, for example, to merge severalPME messages into one PME message or several PME messages, to splitand/or copy a PME message into several PME messages, to copy and/orstore PME messages for temporary and/or long-term periods of time, or toperform other desired tasks associated with a PME message or withseveral PME messages. Additionally or alternatively, switch 530 may beused to create and/or convert a a PME messages. Additionally oralternatively, switch 530 may perform the tasks described above whileswitch 530 is connected between devices that operate in accordance withthe same or different protocols or specifications, for example, betweena device that operates in accordance with PCI specification and a devicethat operates in accordance with PCI Express specification.

[0043] Reference is now made also to FIG. 6, which is a schematicillustration of a PME message-generating switch 690 in accordance withan exemplary embodiment of the present invention, which may be used, forexample, in conjunction with network 550 of FIG. 5. Switch 690 mayinclude, for example, bus 640, bus 650, bus 660, bus 670, bridge 610,bridge 620, and bridge 630. Switch 690 may receive a PME signal from aPCI device 601 connected to bus 640, and may output a PME message toanother device or to a PMC connected to bus 670.

[0044] It should be appreciated that the schematic illustration of FIG.6 is only an exemplary embodiment of a switch in accordance with anaspect of the present invention, and that other implementations of aswitch, bridge, controller, hub and/or router are also within the scopeof the present invention. Further, it should be appreciated thatembodiments of switch 690 may include, for example, memory units,buffers, processors and/or other components (not shown), e.g., tofacilitate the operation of specific implementations or to accommodatespecific requirements or functionalities.

[0045] In an embodiment of the invention, bridge 610, bridge 620 and/orbridge 630 may include, for example, any suitable Point-to-Point (P2P)bridge which may be used for connecting devices, connecting networks,and/or converting data between various formats and/or protocols. Bus640, bus 650, bus 660 and/or bus 670 may include any suitable internaland/or external data bus, which may be used for connecting devicesand/or transferring data, for example, a PCI bus. In an exemplaryembodiment of the present invention, bus 640 may be connected to bridge620, bus 650 may be connected to bridge 630, bus 660 may be connected tobridge 610, and bridges 610, 620 and 630 may be connected to bus 670.

[0046] One or more device, for example, PCI device 601, may be connectedto bus 640. PCI device 601 may send a PME signal, which may betransferred and/or routed using bus 640 to bridge 620. Bridge 620 mayreceive the PME signal, and may create a PME message based on thesource, e.g., identity, location, or other property of the deviceoriginating the PME signal. Specifically, in an exemplary embodiment ofthe present invention, bridge 620 may construct a PME message whichindicates that PCI device 601 is the originating device that sent thePME signal, and/or that a device connected to bus 640 is the originatingdevice that sent the PME signal, and/or includes other data describingthe PME and/or PCI device 601 and/or bus 640. Bridge 620 may send thePME message using bus 670.

[0047] The PME message may be routed using bus 670, and may reachanother device connected to bus 670 (not shown), a PMC connected to bus670 (not shown), or another bridge, for example, bridge 610, in whichcase the PME message may be routed upstream. Bridge 610 may transfer thePME message to another device connected to it using bus 660, either inthe same format as received by bridge 610 or in another format asmodified by bridge 610. It is noted that bridge 620 and/or bridge 610may, for example, create and/or output a PME message based upon anincoming PME signal, create and/or output a PME message based upon anincoming PME message, re-format and/or re-construct a PME message, ormerge several PME signals and/or PME messages into one or more PMEmessage.

[0048] Embodiments of the present invention may be implemented bysoftware, by hardware, or by any combination of software and/or hardwareas may be suitable for specific applications or in accordance withspecific design requirements. Embodiments of the present invention mayinclude units and sub-units, which may be separate of each other orcombined together, entirely or partly, and may be implemented usingspecific, multi-purpose or general processors, or devices as are knownin the art. Some embodiments may include buffers, registers, storageunits and/or memory units, for temporary or long-term storage of data orin order to facilitate the operation of a specific embodiment.

[0049] While certain features of the invention have been illustrated anddescribed herein, many modifications, substitutions, changes, andequivalents may occur to those of ordinary skill in the art. It is,therefore, to be understood that the appended claims are intended tocover all such modifications and changes as fall within the true spiritof the invention.

1. An apparatus comprising a controller to process a data-bearing powermanagement event message received over a link from a device.
 2. Theapparatus of claim 1, wherein said data-bearing power management eventmessage includes an indication of a property of said device.
 3. Theapparatus of claim 2, wherein said property includes an address of saiddevice.
 4. The apparatus of claim 2, wherein said property includes anidentity of said device.
 5. The apparatus of claim 1, wherein saiddata-bearing power management event message includes an indication of aproperty of a power management event.
 6. The apparatus of claim 1,wherein said data-bearing power management event message includes anindication of a type of a power management event.
 7. The apparatus ofclaim 1, wherein said controller is able to send a turn-off message tosaid device over said link.
 8. The apparatus of claim 7, wherein saidcontroller is able to receive an acknowledgment message from said deviceover said link.
 9. The apparatus of claim 1, wherein said controller isable to probe said device.
 10. The apparatus of claim 1, wherein saidcontroller is able to perform an operation based on a content of saiddata-bearing power management event message.
 11. The apparatus of claim1, wherein said controller is able to switch said link from anon-communicative mode to a communicative mode.
 12. The apparatus ofclaim 11, wherein said controller is able to restore clock to said link.13. The apparatus of claim 11, wherein said controller is able torestore power to said link.
 14. The apparatus of claim 11, wherein saidcontroller is able to receive a notice from said device including anindication on a need to switch said link.
 15. The apparatus of claim 14,wherein said controller is able to receive said notice from said deviceout-of-band.
 16. The apparatus of claim 14, wherein said controller isable to receive said notice from said device in accordance withPeripheral Component Interconnect (PCI) Express specification.
 17. Theapparatus of claim 14, wherein said controller is able to receive saidnotice from said device in-band.
 18. The apparatus of claim 14, whereinsaid controller is able to receive said notice from said device byreceiving energy transmitted over said link.
 19. A device able to send adata-bearing power management event message.
 20. The device of claim 19,wherein said data-bearing power management event message includes anindication of a property of said device.
 21. The device of claim 20,wherein said property comprises at least one property selected from thegroup consisting of an address of said device and an identity of saiddevice.
 22. The device of claim 19, wherein said data-bearing powermanagement event message includes an indication of a property of a powermanagement event.
 23. The device of claim 19, wherein said data-bearingpower management event message includes an indication of a type of apower management event.
 24. The device of claim 19, wherein said deviceis able to send an acknowledgement message to a controller.
 25. Thedevice of claim 19, wherein said device is able to send a notice to acontroller including an indication on a need to switch a link connectingsaid device and said controller.
 26. The device of claim 25, whereinsaid device is able to send said notice to said controller out-of-band.27. The device of claim 25, wherein said device is able to send saidnotice to said controller in accordance with Peripheral ComponentInterconnect (PCI) Express specification.
 28. The device of claim 25,wherein said device is able to send said notice to said controllerin-band.
 29. The device of claim 25, wherein said device is able to sendsaid notice to said controller by transmitting energy over said link.30. The device of claim 19, wherein said device comprises a modem. 31.The device of claim 19, wherein said device comprises a printer.
 32. Asystem comprising: a device able to send a data-bearing power managementevent message; a controller able to process said message; and a linkconnecting said device to said controller.
 33. The system of claim 32,comprising a switch able to determine the identity of said device and tocreate said data-bearing power management event message.
 34. The systemof claim 32, comprising a switch able to receive a signal indicating apower management event and to create said data-bearing power managementevent message based on said signal.
 35. The system of claim 32,comprising a switch able to convert a first data-bearing powermanagement event message in a first format to a correspondingdata-bearing power management event message in a second format.
 36. Thesystem of claim 32, wherein said first format is based on PeripheralComponent Interconnect (PCI) specification, and wherein said secondformat is based on Peripheral Component Interconnect (PCI) Expressspecification.
 37. A method comprising sending a data-bearing powermanagement event message from a device.
 38. The method of claim 37,wherein sending the data-bearing power management event messagecomprises sending a data-bearing power management event messageincluding an indication of a property of a source of said data-bearingpower management event message.
 39. The method of claim 38, wherein saidproperty comprises at least one property selected from the groupconsisting of an address of a source of said data-bearing powermanagement event message and an identity of a source of saiddata-bearing power management event message.
 40. The method of claim 37,wherein sending the data-bearing power management event messagecomprises sending a data-bearing power management event messageincluding a type of a power management event.
 41. The method of claim37, further comprising: receiving a message from a controller; andsending an acknowledgment message from said device.
 42. The method ofclaim 37, comprising, before sending said data-bearing power managementevent message, sending a notice to a controller including an indicationof a need to switch a link from a non-communicative mode to acommunicative mode.
 43. The method of claim 42, wherein sending saidnotice comprises sending said notice out-of-band.
 44. The method ofclaim 42, wherein sending said notice comprises sending said notice inaccordance with Peripheral Component Interconnect (PCI) Expressspecification.
 45. The method of claim 42, wherein sending said noticecomprises sending said notice in-band.
 46. The method of claim 42,wherein sending said notice comprises transmitting energy through saidlink.
 47. The method of claim 37, comprising, before sending saiddata-bearing power management event message: determining the identity ofsaid device; and creating said data-bearing power management eventmessage based on said identity.
 48. The method of claim 37, comprising,before sending said data-bearing power management event message:receiving a signal indicating a power management event; and creatingsaid data-bearing power management event message based on said signal.49. The method of claim 37, comprising, before sending said data-bealingpower management event message, converting a first data-bearing powermanagement event message in a first format to a correspondingdata-bearing power management event message in a second format.
 50. Themethod of claim 49, wherein said first format is based on PeripheralComponent Interconnect (PCI) specification, and wherein said secondformat is based on Peripheral Component Interconnect (PCI) Expressspecification.
 51. A method comprising receiving a data-bearing powermanagement event message.
 52. The method of claim 51, further comprisingprocessing said data-bearing power management event message.
 53. Themethod of claim 51, further comprising sending a turn-off message tosaid device.
 54. The method of claim 51, further comprising probing asource of said data-bealing power management event message.
 55. Themethod of claim 51, further comprising performing an operation based ona content of said data-bearing power management event message.
 56. Themethod of claim 51, comprising, before receiving said data-bearing powermanagement event message, switching a link between a device and acontroller from a non-communicative mode to a communicative mode. 57.The method of claim 56, wherein switching said link comprises restoringclock to said link.
 58. The method of claim 56, wherein switching saidlink comprises restoring power to said link.
 59. An article comprising astorage medium having stored thereon instructions that, when executed bya processing platform, result in sending a data-bearing power managementevent message from a device.
 60. The article of claim 59, wherein theinstructions that result in sending the data-bearing power managementevent message result in sending a data-bearing power management eventmessage including an indication of a property of a source of saiddata-bearing power management event message.
 61. The article of claim60, wherein said property comprises at least one property selected fromthe group consisting of an address of a source of said data-bearingpower management event message and an identity of a source of saiddata-bearing power management event message.
 62. The article of claim59, wherein the instructions that result in sending the data-bearingpower management event message result in sending a data-bearing powermanagement event message including a type of a power management event.63. The article of claim 59, wherein the instructions further result in:receiving a message from a controller; and sending an acknowledgmentmessage from said device.
 64. The article of claim 59, wherein theinstructions further result in, before sending said data-bearing powermanagement event message, sending a notice to a controller including anindication of a need to switch a link from a non-communicative mode to acommunicative mode.
 65. The article of claim 64, wherein theinstructions that result in sending said notice result in sending saidnotice out-of-band.
 66. The article of claim 64, wherein theinstructions that result in sending said notice result in sending saidnotice in accordance with Peripheral Component Interconnect (PCI)Express specification.
 67. The article of claim 64, wherein theinstructions that result in sending said notice result in sending saidnotice in-band.
 68. The article of claim 64, wherein the instructionsthat result in sending said notice result in transmitting energy throughsaid link.
 69. The article of claim 59, the instructions further resultin, before sending said data-bearing power management event message:determining the identity of said device; and creating said data-bearingpower management event message based on said identity.
 70. The articleof claim 59, wherein the instructions further result in, before sendingsaid data-bearing power management event message: receiving a signalindicating a power management event; and creating said data-bearingpower management event message based on said signal.
 71. The article ofclaim 59, wherein the instructions further result in, before sendingsaid data-bearing power management event message, converting a firstdata-bearing power management event message in a first format to acorresponding data-bearing power management event message in a secondformat.
 72. The article of claim 59, wherein said first format is basedon Peripheral Component Interconnect (PCI) specification, and whereinsaid second format is based on Peripheral Component Interconnect (PCI)Express specification.
 73. An article comprising a storage medium havingstored thereon instructions that, when executed by a processingplatform, result in receiving a data-bearing power management eventmessage.
 74. The article of claim 73, wherein the instructions furtherresult in processing said data-bearing power management event message.75. The article of claim 73, wherein the instructions further result insending a turn-off message to said device.
 76. The article of claim 73,wherein the instructions further result in probing a source of saiddata-bearing power management event message.
 77. The article of claim73, wherein the instructions further result in performing an operationbased on a content of said data-bearing power management event message.78. The article of claim 73, wherein the instructions result in, beforereceiving said data-bearing power management event message, switching alink between a device and a controller from a non-communicative mode toa communicative mode.
 79. The article of claim 78, wherein theinstructions that result in switching said link result in restoringclock to said link.
 80. The article of claim 78, wherein theinstructions that result in switching said link result in restoringpower to said link.